This invention relates to the expeditious production of a supported particulate catalyst suitable for use in a vapor phase reactor.
Heretofore it has been recognized that the extent of the exposed catalytic surface area often is critical in the acceleration of chemical reactions. Large or coarse bodies of catalyst inherently expose a smaller catalytically active surface area to the reactants and accordingly tend to require the use of larger quantifies of catalyst and larger reactors. This commonly adds significantly to the overall expense of the reaction. On the contrary fine bodies of catalyst (i.e., powders) inherently provide the desired larger surface area per unit mass, but when provided in a bed severely impede the flow of gaseous reactants through such bed in view of their excellent packing characteristics. One commonly must resort to the use of higher and higher throughput pressures in order to achieve a reasonable gas flow rate while in contact with such fine catalyst particles. The need to create and maintain elevated pressures in a gas flow reactor requires the selection of special equipment and added expense. Also, the utilization of the required elevated pressures is not even compatible with many gas-phase reaction systems. Accordingly, fine particles of catalyst commonly are relegated to use in slurry processes where some form of agitation is required to keep the fine particles suspended in the reaction medium so as to maximize particle dispersion and to facilitate good contact between the reactants and the active species on the surfaces of the catalyst particles.
In the past it has been proposed to form an activated catalyst on the surface of a solid which is capable of withstanding the highly elevated temperatures required during the catalyst formation process. For instance ceramic and metal monolithic honeycombs and open mesh materials have been utilized. See, for instance (a) J. W. Hightower, Stud. Surf. Sci. Catal., 1 (Prepn. of Cats. I), 615 to 635 (1976); (b) R. Lacroix, Stud. Surf. Sci. Catal., 1 (Prepn. of Cats. I), 637 to 647 (1976); and (c) C. J. Wright and G. Butler, Stud. Surf. Sci. Catal., 16 (Prepn. of Cats. III), 159 to 167 (1983). In order to enable the catalyst to adhere to such solids they initially are treated with a thin wash coat of a high surface area oxide, such as alumina, silica, titania, etc., together with bonding agents such hydrous alumina or silica which adheres to the solid. See, G. J. K. Acres, A. J. Bird, J. W. Jenkins and F. King, Catalysis (London) Vol. 4, 1, Pages 1 to 30 (1981). The preparation of an appropriate wash coat is not simple in that they are complex mixtures with chemical and physical properties being modified by additives. Milling for prolonged periods of time is often required to give materials with well defined rheological properties. The resulting material is then calcined at a high temperature to give a coating on the monolith or mesh where the catalyst can be prepared and activated. Occasionally the catalytically active material is also present in the wash coat and the catalyst is prepared and activated by high temperature treatment of the resulting coated solids. The preparation and activation of catalysts on these bulky coated monoliths or meshes can be difficult to accomplish without the use of specialized equipment and techniques.
It is an object of the present invention to provide a process for the expeditious formation of a supported particulate catalyst suitable for use in a vapor phase reactor.
It is an object of the present invention to provide a process for the expeditious formation of a supported particulate catalyst wherein preformed solid activated catalytic particles are utilized and are secured to a solid support without any substantial loss of catalytic activity.
It is an object of the present invention to provide a process for the formation of a supported particulate catalyst wherein solid supports of greatly varying configurations and/or compositions can be utilized.
It is an object of the present invention to provide a process for the formation of a supported particulate catalyst which is highly amenable for use during the design of a vapor phase reactor since the configuration of the solid support can be varied and the reaction results compared while utilizing exactly the same catalyst with no variation between batches of catalyst.
It is another object of the present invention to provide an efficient supported particulate catalyst suitable for use in a vapor phase reactor.
It is a further object of the present invention to form a cigarette filter capable of promoting the transformation at ambient conditions of carbon monoxide formed during the combustion of a nearby smoke-producing product to carbon dioxide.
These and other objects as well as the scope, nature and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.